Description.
The circuit diagram of a very simple voltage doubler using NE555 timer is shown here. Here IC NE555 is wired as an astable mutivibrator operating at around 9KHz. The base of the two transistors (Q1 and Q2) is shorted and output of the astable multivibrator (pin 3) is connected to it. When the output of astable multivibrator is low, Q1 will be OFF and Q2 will be ON. The negative terminal of the capacitor C3 will be shorted to ground through T2 and it will be charged to the input supply voltage. When the output of the astable multi vibrator is high, transistor Q1 will be ON and transistor Q2 will be OFF. The capacitor C4 will be charged to the voltage across capacitor C3 plus the input supply voltage (that is double the input voltage). This is how the circuit works.

This voltage doubler circuit can deliver only up to 50mA output current and above that current limit the output voltage will be dramatically reduced. The actual output voltage will be around 19V for a 12V DC input and also the output voltage will be a bit unstable. Anyway, for low current applications this circuit is well enough.

CircuitsToday has introduced an online store where you can buy books that give you a better understanding on the applications of 555 IC. These books have been reviewed in detail and the links to buy them is also provided. Check it out:- 3 Great Books to Learn 555 Timer Circuits and Projects.

Hi Admin and Seetharaman,
Can you possibly direct me how to redesign this circuit to deliver a 2 ampere output?
Is there any changes on the transistors Q1 and Q2?
By the way, what is really the value of C2? IS IT 10nF OR 0.05uF,, are they the of same value?
Thanks.

Hi Adnan When Q2 is on C3 -ve is connected input -ve supply and positive is connected through D1 to +12 volt supply. Hence the capacitor gets charged to 12volt. in the next cycle when Q1 is on and Q2 is off, in comming +12 volt is connected to -ve of the capacitor, which is already charged to 12 volt. since the in comming and capacitor are in series the voltage gets added after D2 you will get twice the input voltage. The capacitor C4 gets charged to 24 volt. For multiplying further refer to net for voltage multiplier circuits for generating very high voltage.
Lowering cannot be done in this circuit